Subvalvular aortic stenosis
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Aortic Stenosis Microchapters |
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Diagnosis |
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Treatment |
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Percutaneous Aortic Balloon Valvotomy (PABV) or Aortic Valvuloplasty |
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Transcatheter Aortic Valve Replacement (TAVR) |
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Case Studies |
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Subvalvular aortic stenosis On the Web |
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American Roentgen Ray Society Images of Subvalvular aortic stenosis |
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Directions to Hospitals Treating Subvalvular aortic stenosis |
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Risk calculators and risk factors for Subvalvular aortic stenosis |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Aortic insufficiency is more common in this form of aortic stenosis and occurs in 50 to 75% of patients.
Epidemiology and Demographics
Aortic subvalvular stenosis is the second most common form of congenital left ventricular outflow tract obtruction and occurs in 8-30% of all forms of left ventricular outflow tract obstruction. The level of obstruction is located just beneath the aortic valve. HOCM (a.k.a. idiopathic hypertrophic subaortic stenosis or IHSS) is not present at birth and is not considered a congenital lesion.
Pathophysiology
There are several varieties of Congenital Aortic Subvalvular Stenosis (or subaortic stenosis):
- Membranous: A fixed localized membrane 0.5 to 2 cm below the level of the aortic valve and attached to the septum and the base of the anterior mitral leaflet.
- Fibromuscular:
- More commonly there is a fibromuscular membrane or tunnel with a significant muscular component which can sometimes be hard to distinguish from IHSS. This is a more severe form and is often associated with a small aortic root.
- Associated aortic insufficiency (AI) is often present due to the high speed jet of blood through the aortic cusps resulting in fibrosis and retraction.
- Congenital anomalies of the mitral valve:
- Attachment to ventricular septum of accessory chordae from anterior mitral leaflet
- Redundant AV valve tissue causing subaortic obstruction.
- Aneurysm of the membranous ventricular septum
Natural History
The symptoms are similar to that of valvular aortic stenosis but begin earlier in infancy or early adulthood.
Diagnosis
Symptoms
The symptoms are similar to that of valvular aortic stenosis and but begin earlier in infancy or early adulthood.
Echocardiography
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Treatment
The membrane can be resected as shown in the videos below:
ACC / AHA Guidelines- Recommendations for Surgical Intervention (DO NOT EDIT)
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Class I1. Surgical intervention is recommended for patients with SubAS and a peak instantaneous gradient of 50 mm Hg or a mean gradient of 30 mm Hg on echocardiography- Doppler. (Level of Evidence: C) 2. Surgical intervention is recommended for SubAS with less than a 50 mm Hg peak or less than a 30 mm Hg mean gradient and progressive AR and an LV dimension at end-systolic diameter of 50 mm or LV ejection fraction less than 55%. (Level of Evidence: C) Class III1. Surgical intervention is not recommended to prevent AR for patients with SubAS if the patient has trivial LVOT obstruction or trivial to mild AR. (Level of Evidence: C) Class IIb1. Surgical resection may be considered in patients with a mean gradient of 30 mm Hg, but careful follow-up is required to detect progression of stenosis or AR. (Level of Evidence: C) 2. Surgical resection may be considered for patients with less than a 50 mm Hg peak gradient or less than a 30 mm Hg mean gradient in the following situations: a. When LV hypertrophy is present. (Level of Evidence: C) b. When pregnancy is being planned. (Level of Evidence: C) c. When the patient plans to engage in strenuous/ competitive sports. (Level of Evidence: C) |
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